Hook and loop fasteners are used when it is desirable to create a refastenable bond between two or more surfaces, such as in clothing or disposable absorbent articles. These fasteners are used in place of buttons, snaps, or zippers.
In general, hook and loop fasteners have a male component and female component. The female component contains numerous upstanding loops on its surface while the male component contains hooks that mechanically engage the female loops, thereby creating a refastenable bond.
Conventionally, nonwoven loop material for hook and loop fasteners is formed of a nonwoven web having a number of loops. The nonwoven web is then attached to a backing material and the loops extend therefrom.
The male component contains a plurality of resilient, upstanding hook-shaped elements. When the male component and the female component are pressed together in a face-to-face relationship to close the fastening device, the male component hooks entangle the female component loops forming a plurality of mechanical bonds between the individual hooks and loops. When these bonds have been created, the components will not generally disengage under normal conditions. This is because it is very difficult to separate the components by attempting to disengage all the hooks at once. However, when a gradual peeling force is applied to the components, disengagement can be easily effected. Under a peeling force, since the hooks are comprised of a resilient material, they will readily open to release the loops.
Manufacture of this type of device is relatively costly.
Conventional hook and loop components are typically formed by making a fabric with a number of woven loops extending outwardly from a backing. The loops may be provided by weaving a base fabric containing supplementary threads to form the loops, or by knitting the loops into a fabric. In other hook and loop components, the loops may be formed by pleating or corrugating processes. The male components of such fastening devices are typically formed by subsequently cutting the loops. The cut loops serve as the hooks of the male component.
These processes generally produce costly hook and loop fastening materials because they are relatively slow. The hook and loop components of such fastening devices are also usually made out of the same relatively expensive material. This material is expensive because the material used in the male component needs to be resilient so that the hooks can disengage from the loop component when the device is open.
In addition, materials made by these processes tend to produce loops having a small area underneath the fiber such that inserting a hook is difficult. Further, the loops tend to have a directional preference, thereby making insertion of the hooks into the loops more difficult. That is, the loops manufactured using conventional methods may tend to lay in one direction such that hooks that point in a different direction will be less likely to engage the loops.
Attempts have been made to make alternative types of female components for fastening devices.
One such attempt is a method for making a nonwoven female component for hook and loop fasteners in which the fastening material is formed by stretching the backing material for the loops in the machine direction prior to application of the nonwoven web. The nonwoven web is then applied to the stretched backing. The stretched backing is then allowed to relax, causing the nonwoven web to bunch such that the loops may be sheered to form catching regions capable of entangling the hooks of a complementary male fastening component. The female components described therein do not appear to be significantly less expense to manufacture than conventional loop components. And, the area underneath the loops is not increased in size to facilitate insertion of the hooks.
In another attempt at making loops for hook and loop fasteners where the loops are joined to a substrate, the loops are manufactured by the process of extruding liquid material through the apertures of a depositing member onto a moving substrate to form the base of the loop, stretching the liquid material in a direction parallel to the plane of the substrate, severing the stretched material to form a distal end which fuses with an adjacent amount of stretched material to form a loop. Such a method does not appear to reduce the cost of manufacture of loops, or increase the area underneath the loops to facilitate hooking.
In still another attempt, generally used in the area of fasteners for disposable diapers, conventional female components for hook and loop fasteners use various relatively tricot knit material; however, they are costly and have various drawbacks because of their manufacturing processes and characteristics. Usually, a loop component is made by a napping or brushing process, or a needle punch process, which requires sensitive energy control in order to not cut the fibers of the loop component. In particular, when the loop fibers are thin in order to match them with relatively small size hooks, greater sensitivity is required. Moreover, knit material inherently tend to have a directional preference due to their manufacturing processes and therefore limit the size or shape of hook components engageable with such tricot knit loop components.